A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements
International audience Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backs...
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ftccsdartic:oai:HAL:hal-00317046v1 2023-11-12T04:08:21+01:00 A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements Chisham, G. Freeman, M. P. British Antarctic Survey (BAS) Natural Environment Research Council (NERC) 2003 https://hal.science/hal-00317046 https://hal.science/hal-00317046/document https://hal.science/hal-00317046/file/angeo-21-983-2003.pdf en eng HAL CCSD European Geosciences Union hal-00317046 https://hal.science/hal-00317046 https://hal.science/hal-00317046/document https://hal.science/hal-00317046/file/angeo-21-983-2003.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317046 Annales Geophysicae, 2003, 21 (4), pp.983-996 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2003 ftccsdartic 2023-10-21T23:07:53Z International audience Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1?2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year's worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced boundary determination algorithm ... Article in Journal/Newspaper Antarc* Antarctica Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Chisham, G. Freeman, M. P. A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1?2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year's worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced boundary determination algorithm ... |
author2 |
British Antarctic Survey (BAS) Natural Environment Research Council (NERC) |
format |
Article in Journal/Newspaper |
author |
Chisham, G. Freeman, M. P. |
author_facet |
Chisham, G. Freeman, M. P. |
author_sort |
Chisham, G. |
title |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_short |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_full |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_fullStr |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_full_unstemmed |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_sort |
technique for accurately determining the cusp-region polar cap boundary using superdarn hf radar measurements |
publisher |
HAL CCSD |
publishDate |
2003 |
url |
https://hal.science/hal-00317046 https://hal.science/hal-00317046/document https://hal.science/hal-00317046/file/angeo-21-983-2003.pdf |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317046 Annales Geophysicae, 2003, 21 (4), pp.983-996 |
op_relation |
hal-00317046 https://hal.science/hal-00317046 https://hal.science/hal-00317046/document https://hal.science/hal-00317046/file/angeo-21-983-2003.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782328675730980864 |